Researchers show how plants tell the time

Posted on 23 October 2013

Plants use sugars to tell the time of day, according to research involving a University of York scientist which is published in Nature today.

Plants, like animals, have a 24 hour 'body-clock' known as the circadian rhythm. This biological timer gives plants an innate ability to measure time, even when there is no light - they don’t simply respond to sunrise, for example, they know it is coming and adjust their biology accordingly. This ability to keep time provides an important competitive advantage and is vital in biological processes such as flowering, fragrance emission and leaf movement.

Dr Mike Haydon, now working at the University of York, was part of a team of scientists from the University of Cambridge’s Department of Plant Sciences studying how plants are able to set and maintain this internal clock. The scientists, who are funded by the Biotechnology and Biological Sciences Research Council (BBSRC), have found that the sugars produced by plants are key to timekeeping.

Plants produce sugar via photosynthesis; it is their way of converting the sun’s energy into a usable chemical form needed for growth and function.

This new research has shown that these sugars also play a role in circadian rhythms. Researchers studied the effects of these sugars by monitoring seedlings in CO2-free air, to inhibit photosynthesis, and by growing genetically altered plants and monitoring their biology. The production of sugars was found to regulate key genes responsible for the 24 hour rhythm.

The accumulation of sugar within the plant provides a kind of feedback for the circadian cycle in plants – a bit like resetting a stopwatch

Dr Mike Haydon

Dr Alex Webb, lead researcher at the University of Cambridge, added: “Our research shows that sugar levels within a plant play a vital role in synchronizing circadian rhythms with its surrounding environment. Inhibiting photosynthesis, for example, slowed the plants internal clock by between 2 and 3 hours.”

The research shows that photosynthesis has a profound effect on setting and maintaining robust circadian rhythms in Arabidopsis plants, demonstrating a critical role for metabolism in regulation of the circadian clock.

Dr Haydon, who performed much of the research and is now based in the Department of Biology at York, said: “The accumulation of sugar within the plant provides a kind of feedback for the circadian cycle in plants – a bit like resetting a stopwatch. We think this might be a way of telling the plant that energy in the form of sugars is available to perform important metabolic tasks. This mirrors research that has previously shown that feeding times can influence the phase of peripheral clocks in animals.”

Notes to editors:

The paper 'Photosynthetic entrainment of the Arabidopsis thaliana circadian clock' is published in Nature. DOI 10.1038/nature12603

BBSRC invests in world-class bioscience research and training on behalf of the UK public. Its aim is to further scientific knowledge, to promote economic growth, wealth and job creation and to improve quality of life in the UK and beyond. Funded by Government, and with an annual budget of around £445m, it supports research and training in universities and strategically funded institutes. BBSRC research and the people it funds are helping society to meet major challenges, including food security, green energy and healthier, longer lives. Its investments underpin important UK economic sectors, such as farming, food, industrial biotechnology and pharmaceuticals. For more information about BBSRC, its science and impact see: www.bbsrc.ac.uk